Conventionally, RFID technology is widely used to perform product management. When an IC tag is attached to a linen product such as a uniform or a sheet used in a hotel, the IC tag is to be subjected to cleaning together with the linen product. Therefore, the IC tag attached to the product must be resistant to external force and resistant to solutions used during cleaning. In consideration thereof, as an IC tag to be attached to a linen product, an IC tag provided with a covered portion made of a rubber material so as to cover an IC tag main body is known (refer to Patent Literature 1).
However, when cleaning is performed, a problem arises in that the IC tag is damaged due to pressure in a spinning process using a pressing machine which is referred to as compression and which is performed after washing by water. A result of an investigation into the causes of this problem will now be described with reference to FIG. 7. FIG. 7 is a schematic cross-sectional view of an IC tag according to a conventional example.
An IC tag 500 according to the conventional example includes an IC chip 510, a flexible printed board (hereinafter, referred to as an FPC 520), and a covered portion 550 which covers a surface of the FPC 520. In the FPC 520, a copper foil 522 to function as an antenna is formed between a base film 521 and a cover film 523. The IC tag 500 according to the conventional example is an electric field type IC tag which requires the IC chip 510 and the copper foil 522 to be electrically connected to each other. To this end, an opening is formed on the cover film 523 and the IC chip 510 is arranged in the opening to fix the IC chip 510 and the copper foil 522 to each other with a solder 530. In addition, in order to prevent detachment of the solder 530 when stress concentrates in a vicinity of the IC chip 510, an underfill 540 obtained by filling epoxy resin or the like is provided.
It was found that damage to the IC tag 500 occurs when the vicinity of the IC chip 510 is bent during compression due to an inability of the vicinity of the IC chip 510 to conform to deformation because of its hardness, and stress concentration causes the copper foil 522 to break.
In addition to electric field type IC tags, there are magnetic field type IC tags. Regarding magnetic field type IC tags, a technique is known in which an IC chip and a coil antenna are unitized by embedding the IC chip and the coil antenna inside a hard resin material such as epoxy. With this technique, since the IC chip and the coil antenna are embedded inside a hard resin material, problems such as disconnection between the IC chip and the coil antenna do not occur. In addition, such unitized IC tags (hereinafter, referred to as magnetic field type tag units) are realized in small sizes and can conceivably be attached to linen products. However, since such a small magnetic field type tag unit has a short communication distance when used on a stand-alone basis, an auxiliary antenna must be provided for practical use (refer to Patent Literature 2). In this case, accuracy of a positional relationship between the magnetic field type tag unit and the auxiliary antenna must be increased.
However, since an IC tag to be attached to a linen product comes into contact with human skin, the IC tag is generally required to be flexible. In addition, as described earlier, the IC tag is subjected to a large force during a spinning process using a pressing machine which is referred to as compression when performing cleaning. Accordingly, a large force may be applied to the IC tag in a state where the IC tag is bent. There are no IC tags capable of increasing the accuracy of a positional relationship between a magnetic field type tag unit and an auxiliary antenna under such conditions.